Monday, September 18, 2006
Saturday's snowfall was a reminder that fall and winter are on their way. These are the seasons in which coughs, colds and serious illnesses such as pneumonia flourish.
Pneumonia is an infection or inflammation of the lungs. It is caused by bacteria, viruses, fungi or other microorganisms. Viral pneumonias can be caused by a variety of illnesses. Common causes are influenza, Respiratory Synctal Virus (RSV) and the herpes or varicella viruses, including those that cause the common cold.
Viral pneumonias are not typically very serious for most people. However, they can be life-threatening in young children, the elderly and anyone whose immune system is very weak.
Symptoms of viral pneumonias usually include low-grade fever of less than 102 degrees Farenheit, coughing up small amounts of mucus, tiredness and muscle aches. Symptoms can last for several days to a few weeks.
Though physicians have been aware of RSV infections in adults for decades, much of the research has been overshadowed by the importance of RSV in children. In a recent article in the New England Journal of Medicine, it was reported that the symptoms of RSV and influenza were similar in adult patients and twice as prevalent.
There are significant public health issues among adults infected with RSV, particularly patients with pre-existing pulmonary and cardiac disease.
RSV was first recognized in 1957 as a cause of bronchiolitis. It is the most commonly identified cause of lower respiratory tract infection or pneumonia in infants and children under one year of age. It was not until the 1970s that RSV was recognized as a serious problem in older adults during outbreaks of the virus in long-term care facilities.
Though pediatricians are keenly aware that RSV may cause serious illness in their patients, most adult caretakers are only recently becoming aware of the impact of this virus during flu season.
Annual outbreaks of RSV and the related Parainfluenza viruses are a given. That, coupled with the frequency of reinfection among high-risk populations, suggests that these lower respiratory viruses impose a considerable disease burden throughout life.
A well-recognized consequence of RSV and some influenza infections is the viral-bacterial interaction. This can cause simultaneous or sequential infections. Because RSV endangers elderly and high-risk adults, the development of effective vaccines would be a healthcare breakthrough. However, RSV causes repeated infections throughout life, and this raises the question of whether it will be possible to provide protective immune responses by vaccination.
The populations that will benefit most from an effective RSV vaccine are infants and the elderly. The World Health Organization has designated RSV as a high-priority germ for vaccine development.
Compounding the challenges of making an effective vaccine is a general lack of public awareness of RSV infection. RSV is an increasingly recognized cause of illness in adults among the medical world, with a disease burden similar to that of nonpandemic influenza A.
- Steven Ross, MD, FAAP, is a pediatrician serving patients in Steamboat Springs and Craig at Seeping Bear Pediatrics.